Display apparatus and electronic apparatus

ABSTRACT

A display apparatus according to the present disclosure includes: a pixel array unit, pixels being arranged in the pixel unit, the pixels each including a driving transistor that includes a plurality of gate electrodes and drives a light emitting unit in response to a video signal applied to one gate electrode of the plurality of gate electrodes; and a control unit that controls gate voltage of a different gate electrode of the driving transistor. Further, an electronic apparatus according to the present disclosure includes the display apparatus having the above-mentioned configuration.

TECHNICAL FIELD

The present disclosure relates to a display apparatus and an electronicapparatus, and particularly to a flat display apparatus in which pixelseach including a light emitting unit are arranged in a matric pattern,and an electronic apparatus including the display apparatus.

BACKGROUND ART

As one of flat (flat panel) display apparatuses, for example, there isan organic EL display apparatus using, as a light emitting unit (lightemitting device), an organic EL device that uses the phenomenon of lightemission when applying an electric field to an organic thin film byusing electroluminescence (EL) of an organic material.

In the flat display apparatus typified by this organic EL displayapparatus, when the characteristics (threshold voltage, mobility, andthe like) of a driving transistor that drives the light emitting unitdiffer for each pixel, the value of current flowing through the drivingtransistor varies between the pixels. As a result, even when the samevoltage is applied to the gate electrode of the driving transistorbetween the pixels, the light emission luminance of the light emittingunit varies between the pixels, which impairs the uniformity of ascreen.

Therefore, each pixel of the flat display apparatus typified by theorganic EL display apparatus has a threshold voltage correction functionof correcting variations in the characteristics, e.g., variations in athreshold voltage V_(th), of the driving transistor driving the lightemitting unit in units of pixels (see, for example, Patent Literature1).

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent Application Laid-open No.2008-287141

DISCLOSURE OF INVENTION Technical Problem

In the above-mentioned correction function of correcting the variationin the characteristics of the driving transistor, correction isperformed in units of pixels. In such a correction function according tothe related art, for example, it is difficult to achieve a sufficientimprovement effect for partial deterioration of the uniformity in thescreen.

It is an object of the present disclosure to provide a display apparatusand an electronic apparatus including the display apparatus that arecapable of improving partial deterioration of the uniformity that cannotbe handled with the function of correction performed in units of pixels.

Solution to Problem

In order to achieve the above-mentioned object, a display apparatusaccording to the present disclosure is characterized by including:

a pixel array unit, pixels being arranged in the pixel unit, the pixelseach including a driving transistor that includes a plurality of gateelectrodes and drives a light emitting unit in response to a videosignal applied to one gate electrode of the plurality of gateelectrodes; and

a control unit that controls gate voltage of a different gate electrodeof the driving transistor. Further, in order to achieve theabove-mentioned object, an electronic apparatus according to the presentdisclosure is characterized by including the display apparatus havingthe above-mentioned configuration.

In the display apparatus or electronic apparatus having theabove-mentioned configuration, threshold voltage of the drivingtransistor can be corrected by controlling the gate voltage of thedifferent gate electrode of the driving transistor. Accordingly, it ispossible to achieve partial correction in the screen for the thresholdvoltage of the driving transistor.

Advantageous Effects of Invention

According to the present disclosure, since partial correction in thescreen can be achieved for the threshold voltage of the drivingtransistor, it is possible to improve partial deterioration of theuniformity that cannot be handled with the function of correctionperformed in units of pixels.

It should be noted that the effect described here is not necessarilylimitative and may be any effect described in the present disclosure.Further, the effects described herein are merely examples and are notlimited, and additional effects may be provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a system configuration diagram schematically showing aspecific configuration of an active matrix display apparatus to whichthe technology of the present disclosure is applied.

FIG. 2 is a circuit diagram showing a circuit example of a pixel in theactive matrix display apparatus to which the technology of the presentdisclosure is applied.

FIG. 3A is an explanatory diagram for the effect onodd-numbered/even-numbered pixel rows due to angled ion implantation,and FIG. 3B is an explanatory diagram for partial deterioration of theuniformity in a screen, e.g., horizontal stripes that occur due to theluminance difference between odd-numbered/even-numbered pixel rows.

FIG. 4A is an equivalent circuit diagram showing a transistor having aneuron MOS structure, and FIG. 4B is a circuit diagram of a pixel usinga transistor having a neuron MOS structure as a driving transistor.

FIG. 5 is a circuit diagram showing a circuit configuration of a mainportion of an organic EL display apparatus according to an example 1.

FIG. 6 is a circuit diagram showing a circuit configuration of a mainportion of an organic EL display apparatus according to an example 2.

FIG. 7 is a circuit diagram showing a circuit configuration of a mainportion of an organic EL display apparatus according to an example 3.

FIG. 8 is a circuit diagram showing a circuit configuration of a mainportion of an organic EL display apparatus according to an example 4.

FIG. 9 is a circuit diagram showing a circuit example of a pixel in anactive matrix display apparatus to which an example 5 is applied.

FIG. 10 is a cross-sectional view showing an example of across-sectional structure of a dual gate TFT.

FIG. 11 is a circuit diagram showing a circuit configuration of a mainportion of an organic EL display apparatus according to an example 5.

FIG. 12 is an outer appearance view of a digital still camera of alens-interchangeable and single-lens-reflex type, FIG. 12A shows a frontview thereof, and FIG. 12B shows a rear view thereof.

FIG. 13 is an outer appearance view of a head mounted display.

MODE(S) FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments for carrying out the technology of the presentdisclosure (hereinafter, referred to as “embodiments”) will be describedin detail with reference to the drawings. The technology of the presentdisclosure is not limited to the embodiments, and various numericalvalues, materials, and the like in the embodiments are merely examples.In the following description, the same components or components havingthe same function will be denoted by the same reference symbols, andduplicate description will be omitted. Note that descriptions will bemade in the following order.

1. Display Apparatus and Electronic Apparatus according to PresentDisclosure, General Description

2. Display Apparatus to which Technology of Present Disclosure IsApplied

-   -   2-1. System Configuration    -   2-2. Pixel Circuit    -   2-3. Basic Circuit Operation    -   2-4. Partial Deterioration of Uniformity in Screen

3. Embodiment of Present Disclosure

-   -   3-1. Transistor Having Neuron MOS Structure        -   3-1-1. Device Structure        -   3-1-2. Operational Principal    -   3-2. Example 1 (Example of Countermeasure against Horizontal        Stripes: Example of Using Neuron MOS)    -   3-3. Example 2 (Modified Example of Example 1)    -   3-4. Example 3 (Modified Example of Example 1/Example 2)    -   3-5. Example 4 (Modified Example of Example 1: Example of        Controlling Back Gate)    -   3-6. Example 5 (Modified Example of Example 1: Example of        controlling One of Dual Gate)

4. Modified Example

5. Electronic Apparatus

-   -   5-1. Specific Example 1 (Example of Digital Still Camera)    -   5-2. Specific Example 2 (Example of Head Mounted Display)

6. Configuration of Present Disclosure

<Display Apparatus and Electronic Apparatus According to PresentDisclosure, General Description>

In a display apparatus and an electronic apparatus according to thepresent disclosure, a control unit may be configured to thresholdvoltage of the driving transistor by controlling the gate voltage of thedifferent gate electrode. Further, the control unit may applypredetermined direct current voltage to the different gate electrode ascontrol voltage. The different gate electrode may be a back gate, or oneof gate electrodes of a dual-gate structure.

In the display apparatus and electronic apparatus according to thepresent disclosure including the above-mentioned favorableconfiguration, the control unit may be configured to control the gatevoltage of the different gate electrode in units of pixel rows of thepixel array unit. Further, the pixels each including the drivingtransistor that includes the plurality of gate electrodes may bearranged in even-numbered pixel rows, odd-numbered pixel rows, or allthe pixel rows of the pixel array unit, and the control unit may beconfigured to control the gate voltage of the different gate electrodein only the even-numbered pixel rows or the odd-numbered rows, or in theall pixel rows.

Further, in the display apparatus and electronic apparatus according tothe present disclosure including the above-mentioned favorableconfiguration, the pixels may each have a threshold voltage correctionfunction of using, as a reference, initialization voltage of the gateelectrode, to which the video signal is applied, of the drivingtransistor, and changing source voltage of the driving transistor towardvoltage obtained by subtracting the threshold voltage of the drivingtransistor from the initialization voltage. Further, the light emittingunit may include an organic electroluminescence device.

<Display Apparatus to which Technology of Present Disclosure is Applied>

[System Configuration]

First, a display apparatus to which the technology of the presentdisclosure is applied, more specifically, an active matrix displayapparatus will be described. FIG. 1 is a system configuration diagramschematically showing a specific configuration of an active matrixdisplay apparatus to which the technology of the present disclosure isapplied.

The active matrix display apparatus is a display apparatus that controlscurrent flowing through an electro-optical device by an active device,e.g., an insulated gate field effect transistor, provided in a pixelcircuit that includes the electro-optical device. Typical examples ofthe insulated gate field effect transistor include a MOS transistor anda TFT (Thin Film Transistor).

Here, an active matrix organic EL display apparatus using an organic ELdevice will be described as an example of a light emitting unit (lightemitting device) of the pixel circuit. The organic EL device is acurrent drive type electro-optical device (self-light emitting device)in which the light emission luminance is changed depending on the valueof current flowing through the device.

As shown in FIG. 1, an organic EL display apparatus 10 to which thetechnology of the present disclosure is applied includes a pixel arrayunit 30 in which a plurality of pixels 20 each including an organic ELdevice are two-dimensionally arranged in a matrix pattern, and a drivingcircuit unit located around the pixel array unit 30. The driving circuitunit includes, for example, a write scanning unit 40, a first drivescanning unit 50, a second drive scanning unit 60, a signal output unit70, and the like mounted on a display panel 80 that includes the pixelarray unit 30, and drives each of the pixels 20 of the pixel array unit30. Note that some or all of the write scanning unit 40, the first drivescanning unit 50, the second drive scanning unit 60, and the signaloutput unit 70 may be provided outside the display panel 80.

Here, in the case where the organic EL display apparatus 10 supportscolor display, one pixel (unit pixel) as a unit for forming a colorimage includes a plurality of sub-pixels. In this case, each of thesub-pixels corresponds to the pixel 20 in FIG. 1. More specifically, inthe display apparatus that supports color display, one pixel includes,for example, three sub-pixels, i.e., a sub-pixel that emits red (R)light, a sub-pixel that emits green (G) light, and a sub-pixel thatemits blue (B) light.

However, the one pixel is not limited to the combination of sub-pixelsof three primary colors (RGB), and one pixel may be configured by addinga sub-pixel of one color or sub-pixels of a plurality of colors to thesub-pixels of three primary colors. More specifically, for example, onepixel may be configured by adding a sub-pixel that emits white (W) lightin order to improve the luminance, or one pixel may be configured byadding at least one sub-pixel that emits light of a complementary colorin order to enlarge the color reproduction range.

In the pixel array unit 30, with respect to the arrangement of thepixels 20 in m rows and n columns, scanning lines 31 (31 ₁ to 31 _(m)),first driving lines 32 (32 ₁ to 32 _(m)), and second driving lines 33(33 ₁ to 33 _(m)) are wired for the corresponding pixel rows along therow direction (arrangement direction of the pixels in the pixel rows).Further, with respect to the arrangement of the pixels 20 in m rows andn columns, signal lines 34 (34 ₁ to 34 _(n)) are wired for thecorresponding pixel columns along the column direction (arrangementdirection of the pixels in the pixel columns).

The scanning lines 31 ₁ to 31 _(m) are respectively connected to theoutput terminal in the corresponding row of the write scanning unit 40.The first driving lines 32 ₁ to 32 _(m) are respectively connected tothe output terminal in the corresponding row of the first drive scanningunit 50. The second driving lines 33 ₁ to 33 _(m) are respectivelyconnected to the output terminal in the corresponding row of the seconddrive scanning unit 60. The signal lines 34 ₁ to 34 _(n) arerespectively connected to the output terminal in the correspondingcolumn of the signal output unit 70.

The write scanning unit 40 includes a shift register circuit and thelike. This write scanning unit 40 performs, when writing signal voltageof a video signal to each pixel 20 of the pixel array unit 30, so-calledline sequential scanning that scans each pixel 20 of the pixel arrayunit 30 in units of rows in a sequential order by sequentially supplyingwrite scanning signals WS (WS₁ to WS_(m)) to the scanning lines 31 (31 ₁to 31 _(m)).

The first drive scanning unit 50 includes a shift register circuit andthe like, similarly to the write scanning unit 40. This first drivescanning unit 50 controls light emission/non-light emission(turning-off) of the pixels 20 by supplying first control signals DS(DS₁ to DS_(m)) to the first driving lines 32 (32 ₁ to 32 _(m)) insynchronization with the line sequential scanning performed by the writescanning unit 40.

The second drive scanning unit 60 includes a shift register circuit andthe like, similarly to the write scanning unit 40. This second drivescanning unit 60 performs control of causing the pixels 20 not to emitlight in the non-light emission period by supplying second controlsignals AZ (AZ₁ to AZ_(m)) to the second driving lines 33 (33 ₁ to 33_(m)) in synchronization with the line sequential scanning performed bythe write scanning unit 40.

The signal output unit 70 selectively outputs signal voltage V_(sig) ofthe video signal that depends on the luminance information supplied froma signal supply source (not shown) (hereinafter, referred to simply as“signal voltage” in some cases), and reference voltage V_(ofs). Here,the reference voltage V_(ofs) is voltage (e.g., voltage corresponding tothe black level of the video signal) as a reference of the signalvoltage V_(sig) of the video signal or voltage close to that, and usedas initialization voltage in a threshold voltage correction operation tobe described later.

The signal voltage V_(sig)/the reference voltage V_(ofs) alternativelyoutput from the signal output unit 70 are written to the pixel 20 of thepixel array unit 30 via the signal lines 34 (34 ₁ to 34 _(n)) in unitsof pixel rows selected by the line sequential scanning performed by thewrite scanning unit 40. That is, the signal output unit 70 adopts adriving mode of line sequential writing in which the signal voltageV_(sig) is written in units of pixel rows (lines).

[Pixel Circuit]

FIG. 2 is a circuit diagram showing a circuit example of the pixel(pixel circuit) 20 in the active matrix display apparatus to which thetechnology of the present disclosure is applied. The light emitting unitof the pixel 20 includes an organic EL device (organicelectroluminescence device) 21 as a self-light emitting device.

As shown in FIG. 2, the pixel 20 includes the organic EL device 21 and adriving circuit that drives the organic EL device 21 by applying currentto the organic EL device 21. A cathode electrode of the organic ELdevice 21 is connected to a cathode wiring 35 as a common power sourceline wired in common for all the pixels 20.

The driving circuit of the organic EL device 21 includes a drivingtransistor 22, a write transistor 23, a light emission controltransistor 24, a switching transistor 25, a holding capacitance 26, andan auxiliary capacitance 27. Here, devices constituting the pixel 20,i.e., the organic EL device 21, the driving transistor 22, the writetransistor 23, the light emission control transistor 24, the switchingtransistor 25, the holding capacitance 26, and the auxiliary capacitance27 are formed on a semiconductor substrate such as a silicon singlecrystalline substrate, as an example.

The driving transistor 22, the write transistor 23, the light emissioncontrol transistor 24, and the switching transistor 25 each include aP-channel transistor, and have a structure of not three, i.e.,source/gate/drain terminals but four, i.e., source/gate/drain/back gateterminals. In addition, to the back gates of the transistors 22 to 25,power source voltage V_(cc) is applied.

In the pixel 20 having the above-mentioned configuration, the writetransistor 23 writes, by sampling the signal voltage V_(sig) suppliedfrom the signal output unit 70 via the signal line 34, the signalvoltage V_(sig) to the gate electrode of the driving transistor 22. Thelight emission control transistor 24 is connected between the powersource line of the power source voltage V_(cc) and the source electrodeof the driving transistor 22, and controls light emission/non-lightemission of the organic EL device 21 under the driving by the firstcontrol signals DS. The switching transistor 25 is connected between thedrain electrode of the driving transistor 22 and a current dischargedestination node (e.g., the cathode wiring 35), and performs control ofcausing the organic EL device 21 not to emit light in the non-lightemission period under the driving by the second control signals AZ.

The holding capacitance 26 is connected between the gate electrode andthe source electrode of the driving transistor 22, and holds the signalvoltage V_(sig) written by the write transistor 23. The drivingtransistor 22 drives the organic EL device 21 by applying drivingcurrent that depends on the holding voltage of the holding capacitance26 to the organic EL device 21. The auxiliary capacitance 27 isconnected between the source electrode of the driving transistor 22 anda node having a fixed potential (e.g., the power source line of thepower source voltage V_(cc)).

[Basic Circuit Operation]

Now, the basic circuit operation of the pixel 20 in the active matrixorganic EL display apparatus 10 having the above-mentioned configurationwill be described.

Note that since the write transistor 23, the light emission controltransistor 24, and the switching transistor 25 are each a P-channeltransistor, the low level state and the high level state of each of thewrite scanning signal WS, the first control signal DS, and the secondcontrol signal AZ are an active state and a non-active state,respectively. Further, the write transistor 23, the light emissioncontrol transistor 24, and the switching transistor 25 are each in aconductive state and a non-conductive state when the write scanningsignal WS, the first control signal DS, and the second control signal AZare in the active state and the non-active state, respectively.

First, while the reference voltage V_(ofs) is output from the signaloutput unit 70 to the signal line 34, the write scanning signal WSbecomes in the active state and the write transistor 23 becomes in theconductive state, so that the reference voltage V_(ofs) is written tothe gate electrode. Accordingly, gate voltage V_(g) of the drivingtransistor 22 becomes the reference voltage V_(ofs).

Further, at the timing of writing the reference voltage V_(ofs), thefirst control signal DS is in a low level state and the light emissioncontrol transistor 24 is in the conductive state. As a result, sourcevoltage V_(s) of the driving transistor 22 becomes the power sourcevoltage V_(cc). At this time, the gate-source voltage V_(gs) of thedriving transistor 22 satisfies the relationship ofV_(gs)=V_(ofs)−V_(cc).

Here, in order to perform a threshold voltage correction operation(threshold voltage correction processing) to be described later, thegate-source voltage V_(gs) of the driving transistor 22 needs to be madelarger than the threshold voltage V_(th) of the driving transistor 22.For that reason, each voltage value is set so that the relationship of|V_(gs)|=|V_(ofs)−V_(cc)|>|V_(th)| is satisfied.

As described above, the initialization operation of setting the gatevoltage V_(g) of the driving transistor 22 to the reference voltageV_(ofs) and the source voltage V_(s) of the driving transistor 22 to thepower source voltage V_(cc) is a preparation (threshold voltagecorrection preparation) operation before performing the next thresholdvoltage correction operation. Therefore, the reference voltage V_(ofs)and the power source voltage V_(cc) are initialization voltage of thegate voltage V_(g) of the driving transistor 22 and initializationvoltage of the source voltage V_(s) of the driving transistor 22,respectively.

Next, when the first control signals DS becomes in the non-active stateand the light emission control transistor 24 becomes in thenon-conductive state, the source electrode of the driving transistor 22becomes in a floating state, and the threshold voltage correctionoperation is started while the gate voltage V_(g) of the drivingtransistor 22 is kept at the reference voltage V_(ofs). That is, thesource voltage V_(s) of the driving transistor 22 starts decreasingtoward voltage (V_(g)−V_(th)) obtained by subtracting the thresholdvoltage V_(th) from the gate voltage V_(g) (=V_(ofs)) of the drivingtransistor 22.

As described above, the operation of changing, by using theinitialization voltage V_(ofs) of the gate electrode of the drivingtransistor 22 as a reference, the source voltage V_(s) of the drivingtransistor 22 toward voltage (V_(ofs)−V_(th)) obtained by subtractingthe threshold voltage V_(th) of the driving transistor 22 from theinitialization voltage V_(ofs) is the threshold voltage correctionoperation. When this threshold voltage correction operation progresses,the gate-source voltage V_(gs) of the driving transistor 22 eventuallyconverges to the threshold voltage V_(th) of the driving transistor 22.This voltage corresponding to the threshold voltage V_(th) is held inthe holding capacitance 26.

Then, the write scanning signal WS becomes in the non-active state andthe write transistor 23 becomes in the non-conductive state, so that thethreshold value correction period is finished. After that, the signalvoltage V_(sig) of the video signal is output from the signal outputunit 70 to the signal line 34, and the potential of the signal line 34is switched from the reference voltage V_(ofs) to the signal voltageV_(sig).

Next, the write scanning signal WS becomes in the active state, so thatthe write transistor 23 becomes in the conductive state, samples thesignal voltage V_(sig), and then writes the sampled signal voltageV_(sig) to the pixel 20. With this write operation of the signal voltageV_(sig) by the write transistor 23, the gate voltage V_(g) of thedriving transistor 22 becomes the signal voltage V_(sig).

At the time of writing the signal voltage V_(sig) of the video signal,the auxiliary capacitance 27 connected between the source electrode ofthe driving transistor 22 and the power source line of the power sourcevoltage V_(cc) acts to suppress the change in the source voltage V_(s)of the driving transistor 22. Then, at the time of driving the drivingtransistor 22 by the signal voltage V_(sig) of the video signal, thethreshold voltage V_(th) of the driving transistor 22 is cancelled outby the voltage corresponding to the threshold voltage V_(th) held in theholding capacitance 26.

At this time, the gate-source voltage V_(gs) of the driving transistor22 is opened (increased) depending on the signal voltage V_(sig).However, the source voltage V_(s) of the driving transistor 22 is stillin a floating state. For that reason, the charges stored in the holdingcapacitance 26 are discharged according to the characteristics of thedriving transistor 22. Then, by the current flowing through the drivingtransistor 22 at this time, charging of the equivalent capacitance ofthe organic EL device 21 is started.

Since the equivalent capacitance of the organic EL device 21 is chargedthe source voltage V_(s) of the driving transistor 22 is graduallydecreased as time passes. At this time, the variation in the thresholdvoltage V_(th) of the driving transistor 22 for each pixel has beencancelled out, and drain-source current I_(ds) of the driving transistor22 depends on a mobility μ of a semiconductor thin film constituting achannel of the driving transistor 22 (hereinafter, referred to simply as“the mobility μ”).

Here, the amount of decrease in the source voltage V_(s) of the drivingtransistor 22 acts to discharge the charges stored in the holdingcapacitance 26. In other words, a negative feedback has been applied tothe holding capacitance 26 by the amount of decrease (amount of change)in the source voltage V_(s) of the driving transistor 22. Therefore, theamount of decrease in the source voltage V_(s) of the driving transistor22 becomes the feedback amount of the negative feedback.

As described above, by applying a negative feedback to the holdingcapacitance 26 by the feedback amount depending on the drain-sourcecurrent I_(ds) flowing through the driving transistor 22, it is possibleto cancel out the dependency of the drain-source current I_(ds) of thedriving transistor 22 on the mobility p. This canceling operation(canceling processing) is a mobility correction operation (mobilitycorrection processing) of correcting the variation in the mobility μ ofthe driving transistor 22 for each pixel. More specifically, since thedrain-source current I_(ds) is increase as a signal amplitudeV_(in)(=V_(sig)−V_(ofs)) of the video signal written to the gateelectrode of the driving transistor 22 is larger, also the absolutevalue of the feedback amount of the negative feedback is increased.Therefore, the mobility correction processing depending on the signalamplitude V_(in) of the video signal, i.e., the light emission luminancelevel is performed. Further, in the case where the signal amplitudeV_(in) of the video signal is kept constant, since the absolute value ofthe feedback amount of the negative feedback is increased as themobility μ of the driving transistor 22 is larger, it is possible toremove the variation in the mobility p for each pixel.

Then, the write scanning signal WS becomes in the non-active state andthe write transistor 23 becomes in the non-conductive state, so that theoperation (processing) of writing signal voltage and correcting themobility is finished. After that, the first control signal DS becomes inthe non-active state and the light emission control transistor 24becomes in the conductive state, so that current is supplied from thepower source line of the power source voltage V_(cc) to the drivingtransistor 22 via the light emission control transistor 24.

At this time, since the write transistor 23 is in the non-conductivestate, the gate electrode of the driving transistor 22 is electricallydisconnected from the signal line 34 and is in a floating state. Here,in the case where the gate electrode of the driving transistor 22 is ina floating state, since the holding capacitance 26 is connected betweenthe gate/source of the driving transistor 22, the gate voltage V_(g) ischanged in synchronization with the change in the source voltage V_(s)of the driving transistor 22.

That is, the source voltage V_(s) and the gate voltage V_(g) of thedriving transistor 22 is increased while maintaining the gate-sourcevoltage V_(gs) held in the holding capacitance 26. Then, the sourcevoltage V_(s) of the driving transistor 22 is increased to lightemission voltage V_(oled) of the organic EL device 21 that depends onthe saturation current of the transistor.

As described above, the operation in which the gate voltage V_(g) of thedriving transistor 22 is changed in synchronization with the change inthe source voltage V_(s) is a bootstrap operation. In other words, thebootstrap operation is an operation in which the gate voltage V_(q) andthe source voltage V_(s) of the driving transistor 22 are changed whilemaintaining the gate-source voltage V_(gs) held in the holdingcapacitance 26, i.e., voltage between both ends of the holdingcapacitance 26.

Then, the drain-source current I_(ds) of the driving transistor 22starys flowing to the organic EL device 21, so that anode voltageV_(ano) of the organic EL device 21 is increased depending on thevoltage I_(ds). When the anode voltage V_(ano) of the organic EL device21 eventually exceeds threshold voltage V_(thel) of the organic ELdevice 21, driving current starts flowing to the organic EL device 21.Accordingly, the organic EL device 21 starts emitting light.

Meanwhile, in the non-light emission period of the organic EL device 21,the second drive scanning unit 60 makes the second control signals AZ inthe active state and the switching transistor 25 in the conductivestate. Since the switching transistor 25 becomes in the conductivestate, via the switching transistor 25, the drain electrode of thedriving transistor 22 (anode electrode of the organic EL device 21) andthe cathode wiring 35 as the current discharge destination node areelectrically short-circuited.

Here, the on-resistance of the switching transistor 25 is much smallerthan that of the organic EL device 21. Therefore, in the non-lightemission period of the organic EL device 21, it is possible to forciblycause current flowing to the driving transistor 22 to flow to thecathode wiring 35 so that the current does not flow to the organic ELdevice 21. Incidentally, in one horizontal period in which thresholdvoltage correction and signal writing are performed, the second controlsignals AZ becomes in the active state. However, in the subsequent lightemission period, the second control signals AZ is in the non-activestate.

The above-mentioned organic EL display apparatus 10 using, as a lightemitting unit of the pixel 20, the organic EL device 21 that is aself-light emitting device has the following characteristics. That is,the organic EL display apparatus 10 has great expectations as anext-generation display because of the excellent image quality(contrast), advantages for thinning, application and development to atransparent display and a flexible display, and the like as comparedwith the liquid crystal display apparatus that is the same flat displayapparatus. Further, by configuring an organic EL on a semiconductorsubstrate such as a silicon single crystalline substrate, applicationsto an electric viewfinder of a digital still camera, a head mounteddisplay as an ultra-small display apparatus have also been started.

Meanwhile, in the organic EL display apparatus 10, the number ofconstituent devices of the pixel 20 is larger than that of the liquidcrystal display apparatus. For example, the pixel 20 shown in FIG. 2includes the four transistors (22 to 25) and the two capacitive devices(26 and 27) as the constituent devices. When the number of constituentdevices of the pixel 20 is large, it is disadvantageous for highdefinition. From such a viewpoint, particularly, in an organic ELdisplay apparatus formed on a semiconductor substrate, a new twist tocause the wiring or the like for driving the pixel 20 to be sharedbetween adjacent pixel rows in the pixel arrangement, i.e., between theodd-numbered pixel row and the even-numbered pixel row is given.Accordingly, the space of the display area (pixel array unit 30) iscompressed to realize high definition.

[Partial Deterioration of Uniformity in Screen]

As described above, in the case of causing the wiring or the like to beshared between the odd-numbered pixel row and the even-numbered pixelrow, a mirror-inverted structure in which the pixel structure of theodd-numbered row and the even-numbered row is symmetrical with respectto the boundary line between the odd-numbered row and the even-numberedrow is adopted. When the pixel structure of the odd-numbered row and thepixel structure of the even-numbered row are each a mirror-invertedstructure as described above, the following phenomena a) and b) occur.

a) In the production process, angled ion implantation shown in FIG. 3Ais generally used. A difference (characteristic difference of thedriving transistor 22 between the odd-numbered row/the even-numberedrow) in the characteristics (threshold voltage, mobility, and the like)of the driving transistor 22 between the odd-numbered row/theeven-numbered row occurs due to deviation of ion-implantation in theproduction process.

b) For example, the coupling potential differs between the odd-numberedrow and the even-numbered row due to the shape difference between thepixel structure of the odd-numbered row the pixel structure of theeven-numbered row caused by mask deviation or the like (couplingdeference depending on the shape of the pixel structure).

As described above, in the general organic EL display apparatus 10, thepixel 20 has a function of correcting the transistor characteristicssuch as the threshold voltage V_(th) and the mobility μ in units ofpixels, and improves the uniformity, e.g., vertical stripes, by usingthis correction function. However, with only the function of correctionperformed in units of pixels, it is insufficient to improve theuniformity for the effect of the above-mentioned characteristicdifference of the driving transistor 22 between the odd-numbered row/theeven-numbered row and the above-mentioned coupling difference dependingon the shape of the pixel structure. As a result, as shown in FIG. 3B,there is a problem of partial deterioration of the uniformity in thescreen, e.g., horizontal stripes that occur due to the luminancedifference between the odd-numbered row/the even-numbered row.

Embodiment of Present Disclosure

In an embodiment of the present disclosure, in order to make it possibleto handle with partial deterioration of the uniformity that cannot behandled with the function of correction performed in units of pixels, atransistor including the plurality of gate electrodes is used as thedriving transistor 22 of the pixel 20. In addition, the organic ELdevice 21 is driven by applying a video signal to one gate electrode ofthe plurality of gate electrodes of the driving transistor 22 while thethreshold voltage V_(th) of the driving transistor 22 is corrected bycontrolling the gate voltage of a different gate electrode of thedriving transistor.

Examples of the transistor including the plurality of gate electrodesinclude a transistor having a neuron MOS structure, and a dual-gatestructure in a back gate unit of a MOS transistor or a TFT (thin-filmtransistor).

[Transistor Having Neuron MOS Structure]

Now, a transistor having a neuron MOS structure will be described. Theequivalent circuit of the transistor having a neuron MOS structure isshown in FIG. 4A. In FIG. 4A, the left side shows a P-channel neuronMOS, and the right side shows an N-channel neuron MOS. Further, as thedriving transistor 22, a pixel circuit using a transistor having aP-channel neuron MOS structure is shown in FIG. 4B.

(Device Structure)

As shown in FIG. 4A, in the transistor having a neuron MOS structure,the gate electrode is in an electrically floating state, a plurality ofgate electrode (two gate electrodes G₁ and G₂ in this example) areprovided on the side opposite to the channel, and these gate electrodesG₁ and G₂ are capacitively-coupled with a floating gate G_(f).

Further, in the case where the transistor having a neuron MOS structureis used as the driving transistor 22, as shown in FIG. 4B, assumption ismade that the signal voltage V_(sig) is applied as gate voltage V₁ ofthe one gate electrode G₁ and control voltage V_(cont) is applied asgate voltage V₂ of the other gate electrode G₂.

(Operational Principal)

In general, the voltage (floating gate voltage) Φ_(F) of the floatinggate G_(f) of the transistor having a neuron MOS structure is given bythe weighted linear sum of the gate voltage V₁, V₂, . . . , V_(n) of theplurality of gate electrodes G₁, G₂, . . . , G_(n) capacitively-coupledwith the floating gate G_(f), as expressed by the following formula (1).

That is, assuming that the capacitances between the floating gate G_(f)and the gate electrodes G₁, G₂, . . . , G_(n) are C₁, C₂, . . . , C_(n),the floating gate voltage Φ_(F) satisfied the following relationship.

$\begin{matrix}{\Phi_{F} = {{\frac{{C_{1}V_{1}} + {C_{2}V_{2}} + \ldots + {C_{n}V_{n}}}{C_{total}}\mspace{14mu} C_{total}} = {\sum\limits_{i = 0}^{n}C_{i}}}} & (1)\end{matrix}$

Note that C_(total) represents the sum of the capacitances between thefloating gate G_(f) and the gate electrodes G₁, G₂ . . . , G_(n).

Assuming the input gate of two terminals (gate electrodes) shown in FIG.4A, the formula (1) is expressed as the following formula (2).

$\begin{matrix}{\Phi_{F} = \frac{{C_{1}V_{1}} + {C_{2}V_{2}}}{C_{1} + C_{2}}} & (2)\end{matrix}$

When this floating gate voltage Φ_(F) exceeds the threshold voltageV_(th) of the transistor, the transistor having a neuron MOS structurebecomes in the conductive state. Therefore, the formula (2) can beexpressed as the following formula (3).

$\begin{matrix}{\Phi_{F} = {\frac{{C_{1}V_{1}} + {C_{2}V_{2}}}{C_{1} + C_{2}} > V_{th}}} & (3)\end{matrix}$

When this formula (3) is solved for the gate voltage V₁, the followingrelationship is satisfied.

$\begin{matrix}{V_{1} > {{\frac{C_{1} + {C2}}{C_{1}}V_{th}} - {\frac{C_{2}}{C_{1}}V_{2}}}} & (4)\end{matrix}$

Note that the formula (3) and the formula (4) are satisfied in the casewhere the transistor having a neuron MOS structure is an N-channel one.

Further, assuming that the threshold voltage of the transistor as seenfrom the gate electrode G₁ of the gate voltage V₁ is V_(th1), thefollowing relationship is established.

$\begin{matrix}{V_{{th}\; 1} = {{\frac{C_{1} + C_{2}}{C_{1}}V_{th}} - {\frac{C_{2}}{C_{1}}V_{2}}}} & (5)\end{matrix}$

This shows that it is possible to freely control the threshold voltageV_(th1) of the transistor as seen from the gate electrode G₁ of the gatevoltage V₁ when arbitrary voltage can be applied to the gate electrodeG₂ as the gate voltage V₂.

Hereinafter, a specific example of realizing partial correction in thescreen in order to make it possible to handle with partial deteriorationof the uniformity that cannot be handled with the function of correctionperformed in units of pixels will be described.

Example 1

An example 1 is an example of a countermeasure against horizontalstripes that occur due to the luminance difference between theodd-numbered rows/even-numbered rows generated by the characteristicdifference of the driving transistor 22 between the odd-numberedrows/even-numbered rows and the coupling difference depending on theshape of the pixel structure. The circuit diagram of the circuitconfiguration of a main portion of an organic EL display apparatusaccording to the example 1 is shown in FIG. 5. In FIG. 5, for the sakeof simplification of the drawing, the pixels 20 in the pixel arrangementof two rows and three columns are shown for the pixel array unit 30.This also applies to the examples to be described later.

In the example 1, in the pixel arrangement of the pixel array unit 30,the driving transistor 22 of the pixel 20 in the odd-numbered rowincludes, for example, a transistor having a neuron MOS structure inwhich two gate electrodes are provided. The driving transistor 22 of thepixel 20 in the even-numbered row includes a normal P-channeltransistor.

Further, in the pixel 20 in the odd-numbered row, the signal voltageV_(sig) of a video signal is applied, as the gate voltage V₁, to onegate electrode of the driving transistor 22 including a neuron MOS.Further, the control voltage V_(cont) as predetermined direct currentvoltage is applied, as the gate voltage V₂, from a control unit 90 to adifferent gate electrode of the driving transistor 22 via a control line36. The control line 36 is commonly wired between the control unit 90and the pixels 20 in the odd-numbered rows.

The control unit 90 supplies, as the control voltage V_(cont), directcurrent voltage of such a voltage value that eliminates the luminancedifference that occurs between the odd-numbered row/the even-numberedrow to the different gate electrode of the driving transistor 22 of thepixel 20 in the odd-numbered row due to the characteristic difference ofthe driving transistor 22 between the odd-numbered row/the even-numberedrow and the coupling difference depending on the shape of the pixelstructure. The voltage value of the control voltage V_(cont) is set tosuch a value that makes the luminance difference between theodd-numbered row/the even-numbered row small, favorably, zero,considering the characteristic difference of the driving transistor 22between the odd-numbered row/the even-numbered row and the couplingdifference depending on the shape of the pixel structure for eachorganic EL display apparatus 10.

As described above, by using a neuron MOS as the driving transistor 22of the pixel 20 in the odd-numbered row and controlling the gate voltageV₂ of the different gate electrode by the control voltage V_(cont), itis possible to control the threshold voltage V_(th) of the drivingtransistor 22 as is apparent from the formula (5). Accordingly, sinceluminance adjustment can be performed for each area (each odd-numberedrow in this example) in the screen, it is possible to prevent horizontalstripes from occurring due to the luminance difference between theodd-numbered row/the even-numbered row generated by the characteristicdifference of the driving transistor 22 between the odd-numbered row/theeven-numbered row and the coupling difference depending on the shape ofthe pixel structure. As a result, it is possible to improve the partialdeterioration of the uniformity that cannot be handled with the functionof correction performed in units of pixels.

Therefore, adopting the configuration in which the wiring or the likefor driving the pixel 20 is shared between the odd-numbered row and theeven-numbered row, and the pixel structure of the odd-numbered row andthe pixel structure of the even-numbered row are each a mirror-invertedstructure does not result in deterioration of the uniformity, such ashorizontal stripes. As a result, by sharing the wiring or the like fordriving the pixel 20 between the odd-numbered row and the even-numberedrow, it is possible to compress the space of the display area, whichcontributes to high definition.

Example 2

An example 2 is a modified example of the example 1. A circuit diagramof a circuit configuration of a main portion of an organic EL displayapparatus according to the example 2 is shown in FIG. 6. In the example1, a configuration in which luminance adjustment is collectivelyperformed for the odd-numbered rows is adopted. Meanwhile, in theexample 2, a configuration in which luminance adjustment is collectivelyperformed for the even-numbered rows is adopted.

In the example 2, in the pixel arrangement of the pixel array unit 30,the driving transistor 22 of the pixel 20 in the even-numbered rowincludes, for example, a transistor having a neuron MOS structure inwhich two gate electrodes are provided. The driving transistor 22 of thepixel 20 in the odd-numbered row includes a P-channel transistor havinga single gate structure.

In the pixel 20 in the even-numbered row, the signal voltage V_(sig) ofa video signal is applied, as the gate voltage V₁, to one gate electrodeof the driving transistor 22 including a neuron MOS. Further, thecontrol voltage V_(cont) as predetermined direct current voltage isapplied, as the gate voltage V₂, from the control unit 90 to thedifferent gate electrode of the driving transistor 22 via the controlline 36. The control line 36 is commonly wired between the control unit90 and the pixels 20 in the even-numbered rows.

The control unit 90 supplies, as the control voltage V_(cont), directcurrent voltage of such a voltage value that eliminates the luminancedifference that occurs between the odd-numbered row/the even-numberedrow to the different gate electrode of the driving transistor 22 of thepixel 20 in the even-numbered row due to the characteristic differenceof the driving transistor 22 between the odd-numbered row/theeven-numbered row and the coupling difference depending on the shape ofthe pixel structure. The voltage value of the control voltage V_(cont)is set to such a value that makes the luminance difference between theodd-numbered row/the even-numbered row small, favorably, zero, similarlyto the example 1.

According to the example 2 having the above-mentioned configuration, itis possible to achieve the same operation and effect as those of theexample 1. That is, it is possible to prevent horizontal stripes fromoccurring due to the luminance difference between the odd-numberedrow/the even-numbered row generated by the characteristic difference ofthe driving transistor 22 between the odd-numbered row/the even-numberedrow and the coupling difference depending on the shape of the pixelstructure, and improve the partial deterioration of the uniformity thatcannot be handled with the function of correction performed in units ofpixels.

Example 3

An example 3 is a modified example of the example 1/the example 2. Acircuit diagram of a circuit configuration of a main portion of anorganic EL display apparatus according to the example 3 is shown in FIG.7. In the example 1, a configuration in which luminance adjustment iscollectively performed for the odd-numbered rows is adopted. In theexample 2, a configuration in which luminance adjustment is collectivelyperformed for the even-numbered rows is adopted. Meanwhile, in theexample 3, a configuration in which luminance adjustment is collectivelyperformed for both of the odd-numbered rows/even-numbered rows isadopted.

In the example 3, in the pixel arrangement of the pixel array unit 30,as each of the driving transistors 22 of all the pixels 20, for example,a transistor having a neuron MOS structure in which two gate electrodesare provided is used. In the pixel arrangement in which the drivingtransistor 22 includes a neuron MOS, control voltage V_(cont1) isapplied, as the gate voltage V₂, from a control unit 91 to the differentelectrode of the driving transistor 22 in the odd-numbered row via thecontrol line 36. Further, control voltage V_(cont2) is applied, as thegate voltage V₂, from a control unit 92 to the different gate electrodeof the driving transistor 22 in the even-numbered row via a control line37.

Each voltage value of the control voltage V_(cont1) and the controlvoltage V_(cont2) is set to such a value that makes the luminancedifference between the odd-numbered row/the even-numbered row small,favorably, zero, considering the characteristic difference of thedriving transistor 22 between the odd-numbered row/the even-numbered rowand the coupling difference depending on the shape of the pixelstructure for each organic EL display apparatus 10.

According to also the example 3 having the above-mentionedconfiguration, it is possible to achieve the same operation and effectas those of the example 1/the example 2. That is, it is possible toprevent horizontal stripes from occurring due to the luminancedifference between the odd-numbered row/the even-numbered row generatedby the characteristic difference of the driving transistor 22 betweenthe odd-numbered row/the even-numbered row and the coupling differencedepending on the shape of the pixel structure, and improve the partialdeterioration of the uniformity that cannot be handled with the functionof correction performed in units of pixels. Further, according to theexample 3, since the threshold voltage V_(th) of the driving transistor22 can be adjusted in both of the odd-numbered row/even-numbered row, itis possible to enlarge the adjustment range of the luminance in both ofthe odd-numbered row/even-numbered row.

Example 4

An example 4 is a modified example of the example 1. A circuit diagramof a circuit configuration of a main portion of an organic EL displayapparatus according to the example 4 is shown in FIG. 8. The example 1is an example in which the transistor having a neuron MOS structure isused as the driving transistor 22, the signal voltage V_(sig) of a videosignal is applied to the one gate electrode, and the gate voltage V₂ ofthe different gate electrode is controlled.

Meanwhile, the example 4 is an example in which voltage of a back gateis controlled in the driving transistor 22 that includes a transistorhaving a structure including the back gate. Specifically, in the pixel20 in the odd-numbered row, the control voltage V_(cont) aspredetermined direct current voltage is applied, as back gate voltage,from the control unit 90 to a back gate of the driving transistor 22having a structure including the back gate via the control line 36. Thecontrol line 36 is commonly wired between the control unit 90 and thepixels 20 in the odd-numbered rows.

The control unit 90 supplies, as the control voltage V_(cont), directcurrent voltage of such a voltage value that eliminates the luminancedifference that occurs between the odd-numbered row/the even-numberedrow to the back gate of the driving transistor 22 of the pixel 20 in theodd-numbered row, similarly to the case of the example 1. The voltagevalue of the control voltage V_(cont) is set to such a value that makesthe luminance difference between the odd-numbered row/the even-numberedrow small, favorably, zero, considering the characteristic difference ofthe driving transistor 22 between the odd-numbered row/the even-numberedrow and the coupling difference depending on the shape of the pixelstructure for each organic EL display apparatus 10.

According to also the example 4 having the above-mentionedconfiguration, it is possible to achieve the same operation and effectas those of the example 1. That is, it is possible to prevent horizontalstripes from occurring due to the luminance difference between theodd-numbered row/the even-numbered row generated by the characteristicdifference of the driving transistor 22 between the odd-numbered row/theeven-numbered row and the coupling difference depending on the shape ofthe pixel structure, and improve the partial deterioration of theuniformity that cannot be handled with the function of correctionperformed in units of pixels.

In the example 4 in which luminance adjustment is collectively performedfor the odd-numbered rows, as a modified example thereof, it is possibleto adopt a configuration in which luminance adjustment is collectivelyperformed for the even-numbered rows similarly to the example 2 or aconfiguration in which luminance adjustment is collectively performedfor both of the odd-numbered rows/even-numbered rows similarly to theexample 3.

Example 5

An example 5 is a modified example of the example 1. A circuit exampleof a pixel in an active matrix display apparatus to which the example 5is applied is shown in FIG. 9. Also in this example, an active matrixorganic EL display apparatus using an organic EL device as a lightemitting unit (light emitting device) of a pixel circuit will bedescribed as an example.

As shown in FIG. 9, the pixel 20 includes the organic EL device 21, anda driving circuit that drives the organic EL device 21 by applyingcurrent to the organic EL device 21. The driving circuit of the organicEL device 21 includes the driving transistor 22, the write transistor23, and the holding capacitance 26.

As each of the driving transistor 22 and the write transistor 23, anN-channel TFT can be used. Note that the combination of conductive typesof the driving transistor 22 and the write transistor 23 shown herein isonly an example, and is not limited thereto. Here, assumption is madethat the organic EL device 21, the driving transistor 22, and theholding capacitance 26 are formed on an insulator such as a glasssubstrate, as an example.

In the driving transistor 22, one electrode (source/drain electrode) isconnected to the anode electrode of the organic EL device 21, and adifferent electrode (source/drain electrode) is connected to the powersource supply line 38. Here, the one electrode represents a metal wiringelectrically connected to one source/drain area, and the differentelectrode represents a metal wiring electrically connected to adifferent source/drain area. Further, depending on the potentialrelationship between the one electrode and the different electrode, theone electrode is a source electrode or a drain electrode in some cases,and the different electrode is a drain electrode or a source electrodein some cases.

A power source potential DS that can be switched between a first powersource potential V_(ccp) and a second power source potential V_(ini)that is lower than the first power source potential V_(ccp) is suppliedfrom a power source supply scanning unit 41 to the power source supplyline 38 to which the different electrode of the driving transistor 22 isconnected, in synchronization with the line sequential scanning by thewrite scanning unit 40. By switching this power source potential DS,light emission/non-light emission (turning-off) of the pixel 20 iscontrolled.

Note that although the circuit configuration of 2Tr1C including twotransistors (Tr) of the driving transistor 22 and the write transistor23, and one capacitive device (C) of the holding capacitance 26 has beenillustrated here the driving circuit of the organic EL device 21, thedriving circuit is not limited thereto.

In the organic EL display apparatus having the above-mentionedconfiguration, the example 5 is an example in which a dual gate TFT isused as the driving transistor 22 and one of a dual gate is controlled.

An example of a cross-sectional structure of a dual gate TFT used as thedriving transistor 22 is shown in FIG. 10. The dual gate TFT includes,for example, a lower gate electrode 82, a first gate insulating film 83,a semiconductor layer 84, a second gate insulating film 85, and an uppergate electrode 86 on a substrate 81 in the stated order. Further, anarea sandwiched between the lower gate electrode 82 and the upper gateelectrode 86 in the semiconductor layer 84 is a channel area 841, andareas of both ends thereof are a source area 842 and a drain area 843. Asource electrode 87 is electrically connected to the source area 842,and a drain electrode 88 is electrically connected to the drain area843.

The example 5 is an example in which voltage of one gate electrode(e.g., the lower gate electrode 82) of the driving transistor 22including the dual gate TFT is controlled. A circuit configuration of amain portion of an organic EL display apparatus according to the example5 is shown in FIG. 11.

As shown in FIG. 11, in the pixel 20 in the odd-numbered row, thecontrol voltage V_(cont) as predetermined direct current voltage isapplied, as gate voltage, from the control unit 90 to one gate electrodeof the driving transistor 22 including the dual gate TFT via the controlline 36. The control line 36 is commonly wired between the control unit90 and the pixel 20 in each odd-numbered row. The driving transistor 22of the pixel 20 in the even-numbered row includes a normal N-channelTFT.

The control unit 90 supplies, as the control voltage V_(cont), directcurrent voltage of such a voltage value that eliminates the luminancedifference that occurs between the odd-numbered row/the even-numberedrow to the different gate electrode of the driving transistor 22, whichincludes the dual gate TFT, of the pixel 20 in the odd-numbered row,similarly to the case of the example 1. The voltage value of the controlvoltage V_(cont) is set to such a value that makes the luminancedifference between the odd-numbered row/the even-numbered row small,favorably, zero, considering the characteristic difference of thedriving transistor 22 between the odd-numbered row/the even-numbered rowand the coupling difference depending on the shape of the pixelstructure for each organic EL display apparatus 10.

According to also the example 5 having the above-mentionedconfiguration, it is possible to achieve the same operation and effectas those of the example 1. That is, it is possible to prevent horizontalstripes from occurring due to the luminance difference between theodd-numbered row/the even-numbered row generated by the characteristicdifference of the driving transistor 22 between the odd-numbered row/theeven-numbered row and the coupling difference depending on the shape ofthe pixel structure, and improve the partial deterioration of theuniformity that cannot be handled with the function of correctionperformed in units of pixels.

In the example 5 in which luminance adjustment is collectively performedfor the odd-numbered rows, as a modified example thereof, it is possibleto adopt a configuration in which luminance adjustment is collectivelyperformed for the even-numbered rows similarly to the example 2 or aconfiguration in which luminance adjustment is collectively performedfor both of the odd-numbered rows/even-numbered rows similarly to theexample 3.

Modified Example

The technology of the present disclosure is not limited to theabove-mentioned embodiment, and various modifications and can be madewithout departing from the essence of the present disclosure. Forexample, in the example 1 to the example 4, a case where the technologyof the present disclosure is applied to a display apparatus in which thedevice constituting the pixel 20 is formed on a semiconductor substratesuch as a silicon single crystalline substrate has been described as anexample. However, the present technology of the present disclosure canbe similarly applied also to a display apparatus in which the deviceconstituting the pixel 20 is formed on an insulator such as a glasssubstrate.

<Electronic Apparatus>

The above-mentioned display apparatus according to the presentdisclosure can be used as a display unit (display apparatus) of anelectronic apparatus in every field in which a video signal input to theelectronic apparatus or a video signal generated in the electronicapparatus is displayed as an image or video. Examples of the electronicapparatus include a television set, a laptop personal computer, adigital still camera, a portable terminal apparatus such as a mobilephone, and a head mounted display. However, the electronic apparatus isnot limited thereto.

By using the display apparatus according to the present disclosure as adisplay unit of an electronic apparatus in every field as describedabove, the following effects can be achieved. That is, according to thedisplay apparatus of the present disclosure, since the partialdeterioration of the uniformity that cannot be handled with the functionof correction performed in units of pixels, such as horizontal stripesthat occur due to the luminance difference between the odd-numberedrow/the even-numbered row, can be improved, it is possible to improvethe image quality of the display unit. In addition, since it is possibleto prevent horizontal stripes due to the luminance difference betweenthe odd-numbered row/the even-numbered row from occurring, the wiring orthe like for driving the pixel between the odd-numbered row and theeven-numbered row can be shared and the space of the display area can becompressed, thereby realizing the high definition of the display unit.

The display apparatus of the present disclosure includes a module-shapeddisplay apparatus having a sealed configuration. By way of example, adisplay module that is formed by attaching a facing portion formed oftransparent glass or the like to a pixel array unit corresponds to thedisplay apparatus. Note that the display module may include a circuitunit for inputting/outputting signals or the like from the outside tothe pixel array unit, a flexible printed circuit (FPC), or the like.Hereinafter, a digital still camera and a head mounted display areexemplified as specific examples of the electronic apparatus using thedisplay apparatus of the present disclosure. It should be noted that thespecific examples described herein are merely illustrative, and thepresent disclosure is not limited thereto.

Specific Example 1

FIG. 12 is an outer appearance view of a digital still camera of alens-interchangeable and single-lens-reflex type, in which FIG. 12Ashows a front view thereof and FIG. 12B shows a rear view thereof. Thedigital still camera of a lens-interchangeable and single-lens-reflextype includes, for example, an interchangeable imaging lens unit(interchangeable lens) 112 on the right side of the front of a cameramain body portion (camera body) 111, and a grip portion 113 to begripped by a photographer on the left side of the front thereof.

Further, a monitor 114 is provided at substantially the center of theback of the camera main body portion 111. An electronic viewfinder(eyepiece window) 115 is provided above the monitor 114. A photographercan visually recognize an optical image of a subject, which is derivedfrom the imaging lens unit 112, and then determine the composition bylooking through the electronic viewfinder 115.

In the digital still camera of a lens-interchangeable andsingle-lens-reflex type having the configuration described above, thedisplay apparatus of the present disclosure can be used as theelectronic viewfinder 115 of the digital still camera. In other words,the digital still camera of a lens-interchangeable andsingle-lens-reflex type according to this example is produced by usingthe display apparatus of the present disclosure as the electronicviewfinder 115 of the digital still camera.

Specific Example 2

FIG. 13 is an outer appearance view of a head mounted display. The headmounted display includes, for example, temple portions 212 on the bothsides of an eyeglass-shaped display unit 211. The temple portions 412are used to be mounted to the head of a user. In this head mounteddisplay, the display apparatus of the present disclosure can be used asthe display unit 211 of the head mounted display. In other words, thehead mounted display according to this example is produced by using thedisplay apparatus of the present disclosure as the display unit 211 ofthe head mounted display.

<Configuration of Present Disclosure>

It should be noted that the present technology may take the followingconfigurations.

[1] A display apparatus, including:

a pixel array unit, pixels being arranged in the pixel unit, the pixelseach including a driving transistor that includes a plurality of gateelectrodes and drives a light emitting unit in response to a videosignal applied to one gate electrode of the plurality of gateelectrodes; and

a control unit that controls gate voltage of a different gate electrodeof the driving transistor.

[2] The display apparatus according to [1] above, in which

the control unit corrects threshold voltage of the driving transistor bycontrolling the gate voltage of the different gate electrode.

[3] The display apparatus according to [1] or [2] above, in which

the control unit applies predetermined direct current voltage to thedifferent gate electrode as control voltage.

[4] The display apparatus according to any one of [1] to [3] above, inwhich

the different gate electrode is a back gate.

[5] The display apparatus according to any one of [1] to [3] above, inwhich

the different gate electrode is one of gate electrodes of a dual-gatestructure.

[6] The display apparatus according to any one of [1] to [5] above, inwhich

the control unit controls the gate voltage of the different gateelectrode in units of pixel rows of the pixel array unit.

[7] The display apparatus according to [6] above, in which

the pixels each including the driving transistor that includes theplurality of gate electrodes are arranged in even-numbered pixel rows,odd-numbered pixel rows, or all the pixel rows of the pixel array unit,and

the control unit controls the gate voltage of the different gateelectrode in only the even-numbered pixel rows or the odd-numbered rows,or in the all pixel rows.

[8] The display apparatus according to any one of [1] to [7] above, inwhich

the pixels each have a threshold voltage correction function of using,as a reference, initialization voltage of the gate electrode, to whichthe video signal is applied, of the driving transistor, and changingsource voltage of the driving transistor toward voltage obtained bysubtracting the threshold voltage of the driving transistor from theinitialization voltage.

[9] The display apparatus according to any one of [1] to [8] above, inwhich

the light emitting unit includes an organic electroluminescence device.

[10] An electronic apparatus, including:

a display apparatus including

-   -   a pixel array unit, pixels being arranged in the pixel unit, the        pixels each including a driving transistor that includes a        plurality of gate electrodes and drives a light emitting unit in        response to a video signal applied to one gate electrode of the        plurality of gate electrodes, and    -   a control unit that controls gate voltage of a different gate        electrode of the driving transistor.

REFERENCE SIGNS LIST

-   -   10 organic EL display apparatus    -   20 pixel    -   21 organic EL device    -   22 driving transistor    -   23 write transistor    -   24 light emission control transistor    -   25 switching transistor    -   26 holding capacitance    -   27 auxiliary capacitance    -   30 pixel array unit    -   31 (31 ₁ to 31 _(m)) scanning line    -   32 (32 ₁ to 32 _(m)) first driving line    -   33 (33 ₁ to 33 _(m)) second driving line    -   34 (34 ₁ to 34 _(n)) signal line    -   35 cathode wiring    -   36, 37 control line    -   38 power source supply line    -   40 write scanning unit    -   41 power source supply scanning unit    -   50 first drive scanning unit    -   60 second drive scanning unit    -   70 signal output unit    -   80 display panel    -   90, 91, 92 control unit

1. A display apparatus, comprising: a pixel array unit, pixels beingarranged in the pixel unit, the pixels each including a drivingtransistor that includes a plurality of gate electrodes and drives alight emitting unit in response to a video signal applied to one gateelectrode of the plurality of gate electrodes; and a control unit thatcontrols gate voltage of a different gate electrode of the drivingtransistor.
 2. The display apparatus according to claim 1, wherein thecontrol unit corrects threshold voltage of the driving transistor bycontrolling the gate voltage of the different gate electrode.
 3. Thedisplay apparatus according to claim 1, wherein the control unit appliespredetermined direct current voltage to the different gate electrode ascontrol voltage.
 4. The display apparatus according to claim 1, whereinthe different gate electrode is a back gate.
 5. The display apparatusaccording to claim 1, wherein the different gate electrode is one ofgate electrodes of a dual-gate structure.
 6. The display apparatusaccording to claim 1, wherein the control unit controls the gate voltageof the different gate electrode in units of pixel rows of the pixelarray unit.
 7. The display apparatus according to claim 6, wherein thepixels each including the driving transistor that includes the pluralityof gate electrodes are arranged in even-numbered pixel rows,odd-numbered pixel rows, or all the pixel rows of the pixel array unit,and the control unit controls the gate voltage of the different gateelectrode in only the even-numbered pixel rows or the odd-numbered rows,or in the all pixel rows.
 8. The display apparatus according to claim 1,wherein the pixels each have a threshold voltage correction function ofusing, as a reference, initialization voltage of the gate electrode, towhich the video signal is applied, of the driving transistor, andchanging source voltage of the driving transistor toward voltageobtained by subtracting the threshold voltage of the driving transistorfrom the initialization voltage.
 9. The display apparatus according toclaim 1, wherein the light emitting unit includes an organicelectroluminescence device.
 10. An electronic apparatus, comprising: adisplay apparatus including a pixel array unit, pixels being arranged inthe pixel unit, the pixels each including a driving transistor thatincludes a plurality of gate electrodes and drives a light emitting unitin response to a video signal applied to one gate electrode of theplurality of gate electrodes, and a control unit that controls gatevoltage of a different gate electrode of the driving transistor.